Napoleon, upon ascending to First Consul of France in 1799, had inherited a chaotic republic; he subsequently created a state with stable finances, a strong bureaucracy, and a well-trained army. In 1805, Austria and Russia waged war against France. In response, Napoleon defeated the allied Russo-Austrian army at Austerlitz in December 1805, which is considered his greatest victory. At sea, the British severely defeated the joint Franco-Spanish navy in the Battle of Trafalgar on October 1805.
This victory secured British control of the seas and prevented the invasion of Britain itself. Prussian concerns about increasing French power led to a resumption of war in October 1806. Napoleon quickly defeated the Prussians, and defeated Russia in June 1807, bringing an uneasy peace to the continent. The peace failed, though, as war broke out in 1809, and a new coalition was soon defeated.

Hoping to isolate Britain economically, Napoleon invaded Iberia, declaring his brother Joseph king of Spain in 1808. The Spanish and Portuguese revolted with British support, and, after six years of fighting, expelled the French from Iberia in 1814. Concurrently, Russia, unwilling to bear economic consequences of reduced trade, routinely violated the Continental System, enticing Napoleon to launch a massive invasion of Russia in 1812. The resulting campaign ended with the dissolution and withdrawal of the French Grande Armée. Encouraged by the defeat, Prussia, Austria, and Russia began a new campaign against France, decisively defeating Napoleon at Leipzig in October 1813 after several inconclusive engagements. The Allies then invaded France, capturing Paris at the end of March 1814 and forcing Napoleon to abdicate in early April. He was exiled to the island of Elba, and the Bourbons were restored to power. However, Napoleon escaped in February 1815, and reassumed control of France. The Allies responded with the Seventh Coalition, defeating Napoleon permanently at Waterloo in June 1815 and exiling him to St Helena, a British territory midway between Africa and Brazil, where he died six years later.

• • • Selected battle • • •

The Battle of Eylau or Battle of Preussisch-Eylau, 7 and 8 February 1807, was a bloody and inconclusive battle between Napoleon's Grande Armée and a Russian Empire army under Levin August von Bennigsen near the town of Preußisch Eylau in East Prussia. Late in the battle, the Russians received a timely reinforcement from a Prussian division. The town is now called Bagrationovsk and it is a part of Kaliningrad Oblast, Russia. The engagement was fought during the War of the Fourth Coalition, part of the Napoleonic Wars.

Napoleon's armies previously smashed the army of the Austrian Empire in the Ulm Campaign and the combined Austrian and Russian armies at the Battle of Austerlitz on 2 December 1805. Austerlitz forced the Austrians to sue for peace and their Russian allies to withdraw from the conflict. On 14 October 1806, Napoleon crushed the armies of the Kingdom of Prussia at the Battle of Jena–Auerstedt. After a rapid pursuit, the broken pieces of the Prussian army were destroyed at the Battles of Prenzlau and Lübeck and in a series of capitulations at Erfurt, Pasewalk, Stettin, Magdeburg, and Hamelin. Eylau was the first serious check to the Grande Armée and the myth of Napoleon's invincibility was badly shaken.

In late January, Bennigsen's Russian army went on the offensive in East Prussia, pushing far to the west. Napoleon reacted by mounting a counter-offensive to the north, hoping to prevent their retreat to the east. After his cossacks captured a copy of Napoleon's orders, Bennigsen rapidly withdrew to the north-east to avoid being cut off. The French pursued for several days and found the Russians drawn up for battle at Eylau. In a vicious evening clash, the French captured the village with heavy losses on both sides. The following day brought even more serious fighting. Early in the battle, a frontal attack by Napoleon failed with catastrophic losses. To retrieve the situation, the emperor launched a massed cavalry charge against the Russians. This bought enough time for the French right wing to throw its weight into the contest. Soon, the Russian left wing was bent back at an acute angle and Bennigsen's army was in danger of collapse. A Prussian corps belatedly arrived and saved the day by pushing back the French right wing. As darkness fell, a French corps tardily appeared on the French left flank. That night Bennigsen decided to retreat, leaving Napoleon in possession of a snowy battlefield covered with thousands of corpses and many more wounded.

He is honoured with a bust in the German Walhalla temple near Regensburg.

The honorary citizen of Berlin, Hamburg and Rostock bore the nickname "Marschall Vorwärts" ("Marshal Forward") because of his approach to warfare. There was a German idiom, "ran wie Blücher" ("on it like Blücher"), meaning that someone is taking very direct and aggressive action, in war or otherwise.